It’s the news we have all been waiting for: the shadowy powers behind the Official Scrabble Players Dictionary have decreed that “aquafaba” (22 points!) is now acceptable – in the US at least. Setting aside the question of who bothers to consult the rules before launching into a full-blown fight about whether “OK” is allowed (spoiler: it is now), what on earth is aquafaba?

Well, as any vegan will tell you, aquafaba is just a fancy name for chickpea cooking water – that murky liquid left at the bottom of the tin, or in the pan after boiling up your dried pulses. According to Sébastien Kardinal and Laura VeganPower, authors of the Aquafaba cookbook, it has exactly the same ratio of water to protein and starch (90:10) as egg whites – which means it can be cooked in much the same way. Chickpea meringues may sound unlikely, but trust me, they’re pure magic.

Aquafaba and vanilla meringues

Heat the oven to 110C/230F/gas ¼. Whisk the chickpea water and salt to soft peaks, then gradually add the sugar and vanilla, still whisking, until thick and glossy. Spoon about 10 big blobs on to a lined tray and bake for about 75 minutes until crisp, then turn off the oven and leave to cool.

Aquafaba mayonnaise

Put all the ingredients apart from the oils in the beaker of a stick blender or the small bowl of a countertop blender and whiz until smooth.

With the mixer still going, gradually incorporate the neutral oil, little by little, until you have a smooth mayo-like substance (it will be runnier than the traditional kind, but will firm up a bit in the fridge).

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Aquafaba chocolate mousse

Melt the chocolate in a microwave or bain marie, stir in the vanilla and then set aside to cool slightly, stirring occasionally.

Whisk the aquafaba, lemon juice and a good pinch of salt until it forms soft peaks. Still whisking, gradually add the caster sugar and whisk to stiff peak stage.

Pour in the melted chocolate and then gently fold it in until the mixture is no longer streaky, being careful to knock as little air out as possible. Divide between 4 small or 2 large bowls and eat immediately.

• This article was amended on 25 September 2018. The chocolate mousse should be eaten immediately, rather than chilled for 2 hours first.